98108a7df21cd54b67f0829fed5d5a7c5b7b9b41
3 * Generator and manager of database load balancing objects
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
24 namespace Wikimedia\Rdbms
;
26 use InvalidArgumentException
;
29 * An interface for generating database load balancers
33 interface ILBFactory
{
34 const SHUTDOWN_NO_CHRONPROT
= 0; // don't save DB positions at all
35 const SHUTDOWN_CHRONPROT_ASYNC
= 1; // save DB positions, but don't wait on remote DCs
36 const SHUTDOWN_CHRONPROT_SYNC
= 2; // save DB positions, waiting on all DCs
39 * Construct a manager of ILoadBalancer objects
41 * Sub-classes will extend the required keys in $conf with additional parameters
43 * @param array $conf Array with keys:
44 * - localDomain: A DatabaseDomain or domain ID string.
45 * - readOnlyReason : Reason the master DB is read-only if so [optional]
46 * - srvCache : BagOStuff object for server cache [optional]
47 * - memStash : BagOStuff object for cross-datacenter memory storage [optional]
48 * - wanCache : WANObjectCache object [optional]
49 * - hostname : The name of the current server [optional]
50 * - cliMode: Whether the execution context is a CLI script. [optional]
51 * - profiler : Class name or instance with profileIn()/profileOut() methods. [optional]
52 * - trxProfiler: TransactionProfiler instance. [optional]
53 * - replLogger: PSR-3 logger instance. [optional]
54 * - connLogger: PSR-3 logger instance. [optional]
55 * - queryLogger: PSR-3 logger instance. [optional]
56 * - perfLogger: PSR-3 logger instance. [optional]
57 * - errorLogger : Callback that takes an Exception and logs it. [optional]
58 * @throws InvalidArgumentException
60 public function __construct( array $conf );
63 * Disables all load balancers. All connections are closed, and any attempt to
64 * open a new connection will result in a DBAccessError.
65 * @see ILoadBalancer::disable()
67 public function destroy();
70 * Create a new load balancer object. The resulting object will be untracked,
71 * not chronology-protected, and the caller is responsible for cleaning it up.
73 * This method is for only advanced usage and callers should almost always use
74 * getMainLB() instead. This method can be useful when a table is used as a key/value
75 * store. In that cases, one might want to query it in autocommit mode (DBO_TRX off)
76 * but still use DBO_TRX transaction rounds on other tables.
78 * @param bool|string $domain Domain ID, or false for the current domain
79 * @return ILoadBalancer
81 public function newMainLB( $domain = false );
84 * Get a cached (tracked) load balancer object.
86 * @param bool|string $domain Domain ID, or false for the current domain
87 * @return ILoadBalancer
89 public function getMainLB( $domain = false );
92 * Create a new load balancer for external storage. The resulting object will be
93 * untracked, not chronology-protected, and the caller is responsible for cleaning it up.
95 * This method is for only advanced usage and callers should almost always use
96 * getExternalLB() instead. This method can be useful when a table is used as a
97 * key/value store. In that cases, one might want to query it in autocommit mode
98 * (DBO_TRX off) but still use DBO_TRX transaction rounds on other tables.
100 * @param string $cluster External storage cluster name
101 * @return ILoadBalancer
103 public function newExternalLB( $cluster );
106 * Get a cached (tracked) load balancer for external storage
108 * @param string $cluster External storage cluster name
109 * @return ILoadBalancer
111 public function getExternalLB( $cluster );
114 * Get cached (tracked) load balancers for all main database clusters
116 * @return LoadBalancer[] Map of (cluster name => LoadBalancer)
119 public function getAllMainLBs();
122 * Get cached (tracked) load balancers for all external database clusters
124 * @return LoadBalancer[] Map of (cluster name => LoadBalancer)
127 public function getAllExternalLBs();
130 * Execute a function for each tracked load balancer
131 * The callback is called with the load balancer as the first parameter,
132 * and $params passed as the subsequent parameters.
134 * @param callable $callback
135 * @param array $params
137 public function forEachLB( $callback, array $params = [] );
140 * Prepare all tracked load balancers for shutdown
141 * @param int $mode One of the class SHUTDOWN_* constants
142 * @param callable|null $workCallback Work to mask ChronologyProtector writes
143 * @param int|null &$cpIndex Position key write counter for ChronologyProtector
145 public function shutdown(
146 $mode = self
::SHUTDOWN_CHRONPROT_SYNC
, callable
$workCallback = null, &$cpIndex = null
150 * Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
152 * @param string $fname Caller name
154 public function flushReplicaSnapshots( $fname = __METHOD__
);
157 * Commit open transactions on all connections. This is useful for two main cases:
158 * - a) To commit changes to the masters.
159 * - b) To release the snapshot on all connections, master and replica DBs.
160 * @param string $fname Caller name
161 * @param array $options Options map:
162 * - maxWriteDuration: abort if more than this much time was spent in write queries
164 public function commitAll( $fname = __METHOD__
, array $options = [] );
167 * Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
169 * The DBO_TRX setting will be reverted to the default in each of these methods:
170 * - commitMasterChanges()
171 * - rollbackMasterChanges()
174 * This allows for custom transaction rounds from any outer transaction scope.
176 * @param string $fname
177 * @throws DBTransactionError
179 public function beginMasterChanges( $fname = __METHOD__
);
182 * Commit changes on all master connections
183 * @param string $fname Caller name
184 * @param array $options Options map:
185 * - maxWriteDuration: abort if more than this much time was spent in write queries
186 * @throws DBTransactionError
188 public function commitMasterChanges( $fname = __METHOD__
, array $options = [] );
191 * Rollback changes on all master connections
192 * @param string $fname Caller name
194 public function rollbackMasterChanges( $fname = __METHOD__
);
197 * Check if a transaction round is active
201 public function hasTransactionRound();
204 * Determine if any master connection has pending changes
207 public function hasMasterChanges();
210 * Detemine if any lagged replica DB connection was used
213 public function laggedReplicaUsed();
216 * Determine if any master connection has pending/written changes from this request
217 * @param float $age How many seconds ago is "recent" [defaults to LB lag wait timeout]
220 public function hasOrMadeRecentMasterChanges( $age = null );
223 * Waits for the replica DBs to catch up to the current master position
225 * Use this when updating very large numbers of rows, as in maintenance scripts,
226 * to avoid causing too much lag. Of course, this is a no-op if there are no replica DBs.
228 * By default this waits on all DB clusters actually used in this request.
229 * This makes sense when lag being waiting on is caused by the code that does this check.
230 * In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters
231 * that were not changed since the last wait check. To forcefully wait on a specific cluster
232 * for a given domain, use the 'domain' parameter. To forcefully wait on an "external" cluster,
233 * use the "cluster" parameter.
235 * Never call this function after a large DB write that is *still* in a transaction.
236 * It only makes sense to call this after the possible lag inducing changes were committed.
238 * @param array $opts Optional fields that include:
239 * - domain : wait on the load balancer DBs that handles the given domain ID
240 * - cluster : wait on the given external load balancer DBs
241 * - timeout : Max wait time. Default: ~60 seconds
242 * - ifWritesSince: Only wait if writes were done since this UNIX timestamp
243 * @throws DBReplicationWaitError If a timeout or error occurred waiting on a DB cluster
245 public function waitForReplication( array $opts = [] );
248 * Add a callback to be run in every call to waitForReplication() before waiting
250 * Callbacks must clear any transactions that they start
252 * @param string $name Callback name
253 * @param callable|null $callback Use null to unset a callback
255 public function setWaitForReplicationListener( $name, callable
$callback = null );
258 * Get a token asserting that no transaction writes are active
260 * @param string $fname Caller name (e.g. __METHOD__)
261 * @return mixed A value to pass to commitAndWaitForReplication()
263 public function getEmptyTransactionTicket( $fname );
266 * Convenience method for safely running commitMasterChanges()/waitForReplication()
268 * This will commit and wait unless $ticket indicates it is unsafe to do so
270 * @param string $fname Caller name (e.g. __METHOD__)
271 * @param mixed $ticket Result of getEmptyTransactionTicket()
272 * @param array $opts Options to waitForReplication()
273 * @throws DBReplicationWaitError
275 public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] );
278 * @param string $dbName DB master name (e.g. "db1052")
279 * @return float|bool UNIX timestamp when client last touched the DB or false if not recent
281 public function getChronologyProtectorTouched( $dbName );
284 * Disable the ChronologyProtector for all load balancers
286 * This can be called at the start of special API entry points
288 public function disableChronologyProtection();
291 * Set a new table prefix for the existing local domain ID for testing
293 * @param string $prefix
295 public function setDomainPrefix( $prefix );
298 * Close all open database connections on all open load balancers.
300 public function closeAll();
303 * @param string $agent Agent name for query profiling
305 public function setAgentName( $agent );
308 * Append ?cpPosIndex parameter to a URL for ChronologyProtector purposes if needed
310 * Note that unlike cookies, this works accross domains
313 * @param float $time UNIX timestamp just before shutdown() was called
316 public function appendShutdownCPIndexAsQuery( $url, $time );
319 * @param array $info Map of fields, including:
320 * - IPAddress : IP address
321 * - UserAgent : User-Agent HTTP header
322 * - ChronologyProtection : cookie/header value specifying ChronologyProtector usage
323 * - ChronologyPositionIndex: timestamp used to get up-to-date DB positions for the agent
325 public function setRequestInfo( array $info );